HIV is increasingly understood as a chronic condition, like diabetes or hypertension. Indeed, it can be, but only for those that are willing and able to make a commitment to take antiretroviral (ARV) medicines every day for the rest of their life. Data suggest that physicians cannot reliably assess adherence, and that patients often get insufficient help with adherence problems from physicians. The long-term goal of this project is to improve adherence to prescribed ARV medication regimens, and thereby health outcomes, of persons with HIV. To achieve these goals the study team will enroll 150 patients with HIV who are taking ARV medications in a randomized, crossover, intervention trial. The proposed project will use both electronic drug exposure monitoring (EDM) and detailed patient interviews to collect information about rates of, and barriers to, ARV medication adherence. In the intervention phase of the study, these data will be fed back to physicians, in the form of a report, before outpatient visits. Primary outcome measures for the intervention study will be changes in adherence as assessed by EDM, and changes in viral loads. To insure a diverse patient population and thus maximize the generalizability of our findings, the study sites are an HIV clinic at an academic medical center, a general medicine clinic at an academic medical center, a community health center, and a private practice. The proposed project will also 1) attempt to improve self-report of medication adherence by determining which self-report items best predict adherence, using BDM as a criterion, 2) examine the relationship of 4 measures of interpersonal care and 11 measures of primary care performance to medication adherence, and 3) describe employment-related barriers adherence, including ARV medication side effects, and determine how strongly these barriers affect adherence. This project is unique because it attempts to better understand and improve physician-patient communication around medication adherence for a prevalent, expensive, and treatable chronic condition.